Web DiscoverCircuits.com

Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com, has 28,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.
We make every effort to link to material posted by the designer. 
Please let us if you would like us to link to your design.

HOME Schematics Discover Forum Hobby Corner Dave's Circuits Electronic Resources Book Corner Contact Info

 

 

DiscoverCircuits.com  --   Hobby Corner
"Hobby Circuits for your Hobby Projects"

Last Updated on:  06/19/2009 03:07:31 PM


1 Amp Current Injector
designed by David A. Johnson, P.E.

I designed and built this thing many years ago. I published the hobby circuit in the now defunct “Radio Elecronics” magazine back in 1992. The electronic circuit injects a precise 1 amp of current into any unknown resistor, up to about two ohms. Two alkaline C cells power the complete circuit. A voltage booster provides the current control circuit with a higher voltage, to insure the electronic circuit operates properly, even as the battery voltage drops. A single LED provides both power monitoring and a low battery indicator.  The current source is activated when a pushbutton switch is pressed.

With a good digital voltmeter, you can use this device to measure resistances down to less than one micro ohm. That is 0.000001 ohms. I often use it to measure contact resistance of a relay or the resistance of big chunk of heavy gauge wire or the resistance of a copper trace on a circuit board. You can also use it to measure the voltage drop of a power diode, when conducting one amp of current.  For more details on this circuit, click here.
Click here to View Circuit
Circuit current injector Circuit current injector
 
HOME Schematics Discover Forum Hobby Corner Dave's Circuits Electronic Resources Book Corner Contact Info

 Linking is welcomed but COPYING any content or graphics to your web site is expressly prohibited.

 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |    Privacy Policy